Techniques to meet the requirements, which are linked to pages with descriptions, code examples, browser and assistive technology support notes, and tests.

Failures to avoid, which are linked to pages with descriptions, examples, and tests.

"Understanding" links to pages that explain the intent of the guideline or success criterion, how it helps people with different disabilities, key terms, and resources.

You can customize what is included in this page by selecting from the Customize this Quick Reference section which Technologies, Levels of success criteria, and Sections of techniques you want to include.

For an introduction to WCAG, Techniques, and Understanding documents, see the WCAG Overview.

Note that even content that conforms at the highest level (AAA) will not be accessible to individuals with all types, degrees, or combinations of disability, particularly in the cognitive language and learning areas. Authors are encouraged to seek relevant advice about current best practice to ensure that Web content is accessible, as far as possible, to this community.

About the Techniques

Note: The basis for determining conformance to WCAG 2.0 is the success criteria, not the techniques. (The success criteria have 3-level numbering (0.0.0) and in this page they are followed by a link "Understanding Success Criterion".) All techniques are informative; that means they are not required. There may be other techniques besides the ones listed here.

New Techniques and Comments

The Techniques for WCAG 2.0 document is updated periodically, and anyone can submit techniques that will be considered for inclusion in an update. Please submit corrections, updates, or new information related to techniques, failures, or other WCAG documentation to the WCAG Working Group, per the instructions for commenting.

Text Alternatives:

Guideline 1.1 Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols or simpler language.Understanding Guideline 1.1

Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.)

Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)

Test: If non-text content is a test or exercise that would be invalid if presented in text, then text alternatives at least provide descriptive identification of the non-text content.

Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.

CAPTCHA: If the purpose of non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception
are provided to accommodate different disabilities.

Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

Situation D: If non-text content is time-based media (including live video-only and live audio-only); a test or exercise that would be invalid if presented in text; or primarily intended to create a specific sensory experience:

Advisory Techniques for 1.1.1 - Non-text Content

General Techniques for Informative Non-Text Content (Advisory)

Identifying informative non-text content (future link)

Keeping short descriptions short (future link)

Describing images that include text (future link)

Providing a longer description of the non-text content where only a descriptive label is required using a technology-specific technique (for an accessibility-supported content technology) for long description listed above (future link)

Providing different sizes for non-text content when it cannot have an equivalent accessible alternative (future link)

Using server-side scripts to resize images of text (future link)

General Techniques for Live Non-Text Content (Advisory)

Linking to textual information that provides comparable information (e.g., for a traffic Webcam, a municipality could provide a link to the text traffic report.) (future link)

General techniques to minimize the barrier of CAPTCHAs

Providing more than two modalities of CAPTCHAs (future link)

Providing access to a human customer service representative who can bypass CAPTCHA (future link)

Note: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.

Audio Control:

1.4.2
If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level. (Level A)Understanding Success Criterion 1.4.2

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Contrast (Minimum):

Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;

Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

Logotypes:
Text that is part of a logo or brand name has no minimum contrast requirement.

Contrast (Enhanced):

Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 4.5:1;

Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content, have no contrast requirement.

Logotypes:
Text that is part of a logo or brand name has no minimum contrast requirement.

Fourth Requirement: Techniques to ensure line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing

Fifth Requirement: Techniques to ensure text can be resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window

Not interfering with the user agent's reflow of text as the viewing window is narrowed (General, Future Link) OR

G146: Using liquid layoutAND using measurements that are relative to other measurements in the content by using one or more of the following techniques:

Note 1:
This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path-dependent input but the underlying function (text input) does not.

Note 2:
This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

No Keyboard Trap:

2.1.2 If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away. (Level A)Understanding Success Criterion 2.1.2

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Sufficient Techniques for 2.1.3 - Keyboard (No Exception)

No additional techniques exist for this Success Criterion. Follow techniques for Success Criterion 2.1.1. If that is not possible because there is a requirement for path-dependent input, then it is not possible to meet this Level AAA Success Criterion.

Timing Adjustable:

Turn off: The user is allowed to turn off the time limit
before encountering it; or

Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or

Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or

Real-time Exception: The time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or

Essential Exception: The time limit is essential and extending it would invalidate the activity; or

20 Hour Exception: The time limit is longer than 20 hours.

Note: This success criterion helps ensure that users can complete tasks without unexpected changes in content or context that are a result of a time limit. This success criterion should be considered in conjunction with
Success Criterion 3.2.1, which puts limits on changes of content or context as a result of user action.

Pause, Stop, Hide:

Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and

Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.

Note 2:
Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Note 3:
Content that is updated periodically by software or that is streamed to the user agent is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so.

Note 4:
An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users and if not indicating progress could confuse users or cause them to think that content was frozen or broken.

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Note: Different sites may address this Success Criterion in different ways. An audio version of the content may be helpful to some users. For some people who are deaf, a sign language version of the page may be easier to understand than a written language version since sign language may be their first language.
Some sites may decide to do both or other combinations. No technique will help all users who have difficulty. So different techniques are provided as sufficient techniques here for authors trying to make their sites more accessible. Any numbered technique or combination above can be used by a particular site and it is considered sufficient by the Working Group.

Advisory Techniques for 3.1.5 - Reading Level

Providing text for navigational and landing pages that requires reading ability that is less advanced than the lower secondary education level (future link)

Note 1:
Text alternatives that are "consistent" are not always "identical." For instance, you may have an graphical arrow at the bottom of a Web page that links to the next Web page. The text alternative may say "Go to page 4." Naturally, it would not be appropriate to repeat this exact text alternative on the next Web page. It would be more appropriate to say "Go to page 5". Although these text alternatives would not be identical, they would be consistent, and therefore would satisfy this Success Criterion.

Note 2:
A single non-text-content-item may be used to serve different functions. In such cases, different text alternatives are necessary and should be used. Examples can be commonly found with the use of icons such as check marks, cross marks, and traffic signs. Their functions can be different depending on the context of the Web page. A check mark icon may function as "approved", "completed", or "included", to name a few, depending on the situation. Using "check mark" as text alternative across all Web pages does not help users understand the function of the icon. Different text alternatives can be used when the same non-text content serves multiple functions.

Advisory Techniques for 3.2.4 - Consistent Identification

Ensuring that the text alternative conveys the function of the component and what will happen when the user activates it (future link)

Using the same non-text content for a given function whenever possible (future link)

Note: The techniques at the end of the above list should be considered "last resort" and only used when the other techniques cannot be applied to the page. The earlier techniques are preferred because they increase accessibility to a wider user group.

Techniques for providing suggestions to the user (Advisory)

Providing a text description that contains information about the number of input errors, suggestions for corrections to each item, and instructions on how to proceed (future link)

Providing a text description that contains suggestions for correction as the first item (or one of the first items) of content, or emphasizing this information in the content (future link)

Displaying errors and suggestions in the context of the original form (for example, re-displaying a form where input errors and suggestions for correction are highlighted and displayed in the context of the original form) (future link)

Parsing:

4.1.1 In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features. (Level A)Understanding Success Criterion 4.1.1

Note: Start and end tags that are missing a critical character in their formation, such as a closing angle bracket or a mismatched attribute value quotation mark are not complete.

Note: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification.

Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided.

Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided.

Note 1:
Although conformance can only be achieved at the stated levels, authors are encouraged to report (in their claim) any progress toward meeting success criteria from all levels beyond the achieved level of conformance.

Note 2:
It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.

Advisory Techniques for Conformance Requirement 1 - Conformance Level

Not displaying content that relies on technologies that are not accessibility-supported when the technology is turned off or not supported. (future link)

Using metadata to allow location of a conforming alternative version from the URI of a non-conforming page (future link)

2. Full pages:Conformance (and conformance level) is for full Web page(s) only, and cannot be achieved if part of a Web page is excluded.

Note 1:
For the purpose of determining conformance, alternatives to part of a page's content are considered part of the page when the alternatives can be obtained directly from the page, e.g., a long description or an alternative presentation of a video.

3. Complete processes: When a Web page is one of a series of Web pages presenting a process (i.e., a sequence of steps that need to be completed in order to accomplish an activity), all Web pages in the process conform at the specified level or better. (Conformance is not possible at a particular level if any page in the process does not conform at that level or better.)

Example: An online store has a series of pages that are used to select and purchase products. All pages in the series from start to finish (checkout) conform in order for any page that is part of the process to conform.

5. Non-Interference: If
technologies are used in a way that is not accessibility supported, or if they are used in a non-conforming way, then they do not block the ability of users to access the rest of the page. In addition, the Web page as a whole continues to meet the conformance requirements under each of the following conditions:

when any technology that is not relied upon is turned on in a user agent,

when any technology that is not relied upon is turned off in a user agent, and

when any technology that is not relied upon is not supported by a user agent

In addition, the following success criteria apply to all content on the page, including content that is not otherwise relied upon to meet conformance, because failure to meet them could interfere with any use of the page:

1.4.2 - Audio Control,

2.1.2 - No Keyboard Trap,

2.3.1 - Three Flashes or Below Threshold, and

2.2.2 - Pause, Stop, Hide.

Note: If a page cannot conform (for example, a conformance test page or an example page), it cannot be included in the scope of conformance or in a conformance claim.